There are many types of industrial scrubbing equipment used to scrub floors and/or other surfaces in various industrial environments. Most of these devices have many features in common. They are generally self-propelled devices containing a reservoir for holding a detergent solution. There is some provision for transferring the detergent solution to the surface to be scrubbed and a brush for working the solution on such surface. Scrubbers generally have a squeegee and vacuum fan system to retrieve the scrubbing solution from the surface after the surface has been scrubbed with the detergent solution and transfer the scrubbing solution to a tank in the body of the scrubber.
A common problem arising in the recovery process is the foaming of the scrubbing solution as it is transferred from the surface to the tank. This foaming is a result of the high recovery velocity of the scrubbing solution, rapid changes in the velocity of the solution and turbulence produced during such changes. A further problem is that the solution impinges on the wall upon entering the tank causing spray to form and causing the solution to flow along the walls of the tank and into the outlet duct. An additional problem is that high velocity air entering the tank, with or without solution, will agitate the surface of the solution in the tank thereby causing foam and spray to form. The high velocity, rapid changes in velocity, turbulence, and the impingement on the wall agitate the scrubbing solution causing foam and spray to develop. Industrial floor scrubbers desirably are compact in design to operate effectively and are highly maneuverable. This need for compactness accentuates the potential problems in foam and spray generation and control. Often detergents used in the cleaning solutions are high foamers. In addition, the soilage that is scrubbed from industrial or commercial plant floors will frequently contain high foaming agents. Illustrative of such agents are drawing compounds and coolant cutting oils used in metal fabrication plants, cleaning compounds used in a wide variety of industries, spilled food products and detergents in food warehouses, leak detectors in tank fabrication, chemical additives in many industrial processes, and the like.
The foaming and spray formation can produce various severe problems. It can reduce drastically the volume available in the tank for the recovered solution. The foam fills the tank and exits through the vacuum fan with the expelled air. When excess foam is present the machine must be stopped, driven to a cleaning station, cleaned out and refilled. The machine may then be sent back out on location to scrub. This is costly in lost time and labor. The foam and spray passing through the fan is dirty and contains many harmful suspended and dissolved materials. This can accelerate corrosion of the fan and other scrubber machine parts exposed to the effluent. The effluent may also corrode and contaminate the products, equipment, and the structures of facilities in which the machine is operated. The effluent is obnoxious to people and in many facilities will contain substances dangerous to health. In such instances the levels of these substances must be closely controlled. Industries such as lead plants, asbestos plants, pesticide plants, and warehouses, and chemical plants are illustrations of instances where toxic substances must be controlled. It therefore is important that the spray and foam formation be controlled and not allowed to be expelled into the atmosphere with the air from industrial scrubbers.
The foam and spray formation problem is increased as the level of the recovered solution approaches the upper portion of the tank near the vacuum duct leading to the fan. This is a major concern with typical one or two tank recycling industrial floor scrubbers. Such recycling systems operate with full tanks for most of their scrubbing operation. Illustrative of this type of scrubber machine is that described in U.S. Pat. No. 3,753,777 (Thomsen et al) and U.S. patent application Ser. No. 916,929 filed June 19, 1978.
It has been found highly advantageous in the present invention to provide a scrubber with apparatus for recovering the scrubbing solution under conditions which suppress the formation of foam and spray.